1. Field of the Invention
The present invention relates to liquid development devices, image forming apparatuses, and image forming systems.
2. Description of the Related Art
There are known image forming apparatuses that include, for example, a photoconductor that serves as an example of an image bearing body for bearing a latent image, and a liquid development device for developing the latent image bore by the photoconductor with liquid developer (which is also referred to simply as “developer” below). When such a type of image forming apparatus receives image signals etc. from external devices such as host computers, it forms a latent image on the photoconductor. Then, with the rotation of the photoconductor, the latent image formed on and bore by the photoconductor reaches a developing position where it is developed by the liquid development device, and thus a developer image is formed on the photoconductor. (See, for example, JP 2001-282002A.)
(1) In order to achieve such functions as to develop the latent image formed on the photoconductor, liquid development devices of the type described above have a developer retaining roller having recesses, which are for retaining liquid developer, provided in the surface of the roller, and a supplying roller for supplying the liquid developer to the developer retaining roller.
In these liquid development devices, the liquid developer supplied to the developer retaining roller by the supplying roller is retained in the recesses provided in the surface of the developer retaining roller.
However, in these liquid development devices, the liquid developer that is supplied to the developer retaining roller by the supplying roller may get fixed in the recesses of the developer retaining roller.
(2) Another type of liquid development device is provided with a retaining roller having recesses, which are for retaining liquid developer, provided in the surface of the roller, a supplying roller for supplying the liquid developer to the retaining roller, and an amount-restricting member for restricting the amount of the liquid developer retained in the recesses. The upper edge of the supplying roller is located above the lower edge of the retaining roller in the vertical direction.
In these conventional liquid development devices, the supplying roller arranged below the retaining roller supplies the liquid developer to the retaining roller by causing the liquid surface of the liquid developer to rise. However, when the amount of liquid developer in the liquid development device becomes small and the level of the liquid surface drops, the amount of liquid developer supplied to the retaining roller by the supplying roller may also decrease. One countermeasure that has been devised is to arrange the upper edge of the supplying roller above the lower edge of the retaining roller in the vertical direction such that the supplying roller draws up the liquid developer to supply it to the retaining roller. In this way, it is possible to supply the liquid developer more effectively when the amount of liquid developer in the liquid development device becomes small.
However, in such liquid development devices, a shortage of the liquid developer may locally occur on the retaining roller. For example, the amount of liquid developer retained in the recesses may decrease if the liquid developer retained in the recesses of the retaining roller flows out from those recesses when the retaining roller rotates.
(3) Another type of liquid development device is provided with a retaining roller for retaining liquid developer to be supplied to a developer bearing body, a carrying roller for carrying the liquid developer to the retaining roller, an amount-restricting member for restricting the amount of the liquid developer on the retaining roller, and a containing section for containing the liquid developer, in order to achieve such functions as to develop the latent image formed on the photoconductor.
In these types of liquid development devices, the amount of the liquid developer, which has been carried from the containing section to the retaining roller by the carrying roller and retained by the retaining roller, is restricted by the amount-restricting member, and then the liquid developer is supplied to the developer bearing body. The liquid developer supplied to the developer bearing body is then used for developing the latent image.
However, in such liquid development devices, the liquid developer may pass over the amount-restricting member when the carrying roller carries the liquid developer to the retaining roller.
For example, if the carrying roller is located in the lower section of the amount-restricting member, the liquid developer is raised due to its viscosity when the carrying roller carries the liquid developer to the retaining roller, and the raised liquid developer may pass over the amount-restricting member through a gap provided between. the amount-restricting member and the containing section, which is a separate member. In other cases, the liquid developer may scatter when the carrying roller carries the liquid developer, and the scattered liquid developer may pass over the amount-restricting member through the gap between the amount-restricting member and the containing section. Further, if the carrying roller carries a large amount of liquid developer, then the tendency for the liquid developer to pass over the amount-restricting member becomes even larger.
(4) Another type of liquid development device is provided with a developer bearing roller that is capable of bearing liquid developer from the side on one end of the developer bearing roller up to the side on the other end along the axial direction thereof, a containing section for containing the liquid developer, and a carrying roller for carrying the liquid developer that is to be bore by the developer bearing roller, in order to achieve such functions as to develop the latent image formed on the photoconductor.
In such liquid development devices, the liquid developer carried by the carrying roller is bore by the developer bearing roller from the side on one end of the developer bearing roller up to the side on the other end along the axial direction thereof, and the liquid developer bore by the developer bearing roller is used for developing the latent image bore by the photoconductor.
However, in such liquid development devices, deviation may occur in the liquid level of the liquid developer contained in the containing section.
For example, latent images that are bore by the image bearing body and that are subjected to development are more likely to be formed in the central section in the axial direction of image bearing body rather than at the sides on both ends thereof. In this case, the liquid development device will develop the latent image using the liquid developer bore on the central section in the axial direction of the developer bearing roller. If latent images formed in the central section of image bearing body are continuously developed, then only the liquid developer on the central section in the longitudinal direction of the containing section, which corresponds to the axial direction, will be used for development. As a result, the liquid level of the liquid developer at the central section in the longitudinal direction of the containing section becomes low, and the liquid level of the liquid developer at the sides on both ends becomes high. Therefore, deviation will occur in the liquid level of the liquid developer contained in the containing section.